Wideband code division multiple access (WCDMA) opens the network interface R7 protocol, and introduces a multiple input multiple output (MIMO) technology. The MIMO technology is an enhanced version of high speed downlink packet access (HSDPA), and is designed to multiply peak throughput. In the evolution from the HSDPA to the MIMO, the same carrier is generally shared by the MIMO and the HSDPA.
When the MIMO and the HSDPA share a carrier, to avoid deterioration of the performance of the HSDPA in the transmit diversity mode, a primary/secondary pilot mode is applicable, as shown in FIG. 1. FIG. 1 is a schematic networking diagram of MIMO and HSDPA in a primary/secondary pilot mode. In FIG. 1, the MIMO, the Primary Common Pilot Channel (P-CPICH), the HSDPA, and the R99 employ a single-transmitting mode. The MIMO signals and the HSDPA signals from two power amplifiers (PAs) are carried over one carrier f1, but the R99 signals are carried over another carrier f2; moreover, PA1 has two frequencies f1 and f2, but PA2 has only one frequency f1, which leads to imbalance of power between PA1 and PA2.
In the prior art, to keep power balance between antennas when the MIMO coexists with the conventional HSDPA, the signals output from a single antenna are multiplied by an orthogonal virtual antenna mapping (VAM) matrix. In this way, the power is balanced between two PAs.
However, after all output signals are multiplied by the VAM matrix and output, the performance of the HSDPA does not fluctuate, and cannot be enhanced.